July 1 of the assessment year or within 30 days of when a Change of Value notice or other determination was mailed by the Assessor's Office, whichever date is later.
If the petition is mailed, it must be postmarked by midnight of the deadline. Petitioners may hand deliver the petition to the Board Clerk and have it date stamped. If appealing other Assessor determinations, for example, denial of an application of current use or removal of a classification from property, citizens have 30 days from the date of the mailing of notification. Non-assessment appeals have the same appeal deadline, July 1 or 30 days after the notice, whichever is later.
Pursuant to WAC 458-14-116(6)(a): In counties with a multiyear revaluation cycle, once the board has issued a decision with respect to a taxpayer's real property, and when there has been no intervening change in assessed value, any subsequent appeal to the board by the same taxpayer relating to the same property shall be treated as a motion for reconsideration. The board must hold a hearing on the appeal/motion only if the taxpayer can show that there is newly discovered evidence that materially affects the basis for the board's decision and the taxpayer can show that the evidence could not with reasonable diligence have been discovered and produced at the original hearing. This evidence must be submitted along with the appeal.